An edge restraint is provided for maintaining hard surfaces such as paving stones within a predetermined boundary.
Hard surfaces, such as paving stones, used for various types of traffic are placed over a base surface such as sand or gravel which is as level as possible. The base surface provides vertical support for the paving stones. However, when the stones are loaded with traffic from above, there is a lateral or horizontal force outward which is not adequately controlled by the level base surface. This horizontal force tends to shift the paving stones horizontally creating wider cracks and extending the outer boundary of the paved surface.
Therefore, it is desirable to have some type of edging material along the outside perimeter of the installed paving stones to maintain these paving stones within a fixed boundary such that horizontal forces will not cause the paving stones to separate or spread horizontally outward.
In certain known arrangements, the paved area abuts masonry edges which can be preformed such as bricks, or which can be in the form of poured concrete. Customarily, a band of concrete is poured deep enough and wide enough to provide the necessary edging for the anticipated load. If the load is not too heavy, this process can also be done by laying bricks which are held together by mortar.
A fundamental problem with masonry edging is that in order to provide an adequate restraint edge, this edging is often expensive, time consuming to install, and tends to take up a lot of space. The expense largely results from the fact that it is quite time consuming to prepare the necessary forms and then pour and finish the concrete after the installation of all the paving stones. Further, the complications involved with pouring concrete may also be involved. These complications can include problems with moist or wet soil or inclement weather during installation.
Another problem with the use of a concrete restraint is that after repeated force and aging, cracks or chips may form in the concrete and eventually ruin the integrity of the restraint. Other problems include the excessive weight of the materials used such as the blocks or bricks, or the concrete alone.
An alternative to the use of concrete or masonry edging is the use of preformed edge restraints. Examples of metal edge restraints used in combination as a curb are shown in several patents, for example, U.S. Pat. Nos. 379,401; 398,630 and 670,001. In U.S. Pat. No. 806,563, an example of an edge restraint, combination curb is also shown made from a combination of steel and concrete. All of these metal edge restraints share a common problem of rust corrosion and difficulty of handling. It is desirable to have a rather permanent edge restraint to avoid the expense and labor required to dig up and remove corroded edge restraints no longer strong enough to provide support, and to install replacement edge restraints.
With respect to the inconvenience and expense, first, these steel panels can be rather heavy. Further such panels are extremely difficult to manipulate. The steel restraints have little or no flexibility, rendering the restraints difficult to use with irregular patterned edge borders of paving stones. Also, to facilitate handling due to the excessive weight and the absence of flexibility to fit irregular patterns, these restraints require separate, short sections which are subsequently attached together when installed.
Also, as the concrete is obviously not flexible, irregular shaped pavement borders could not be easily provided. Although preformed curved sections may be available, it would be difficult to match these with actual dimensions of irregular surfaces and angles at the site of installation. This is especially the case with concrete block sections which would be extremely difficult to cut to a desired size and definitely cannot be kept.
Aluminum edge restraints may also be used. However, aluminum lacks strong structural resistance unless the restraint wall is extremely thick, thereby increasing the expense and increasing the difficulty in use due to decreased flexibility and increased weight. To be strong enough to successfully hold the paving stone border, the aluminum restraint would have to have an increased thickness, and therefore decreased flexibility rendering manipulation for irregular paving stone borders difficult.
Another problem shared by these edge restraints is that in all of these examples, the edge restraint is used in an attempt to prevent horizontal movement of paving stones by merely absorbing a horizontal force applied against the edge wall. The wall is only backed by the earth on the side of the wall opposite the paving stones. Dirt shifts under forces from a horizontal direction. None of these patents address converting the horizontal force applied from the paving stones into a vertical force down into the ground. Dirt is more likely to shift when the force is in a horizontal direction than if the force is down into the ground. Therefore, these restraint systems discussed above tend to give into horizontal forces.
A related problem associated with these systems is the absolute requirement for dirt or gravel, commonly referred to as backfill, filled in behind the wall for support. These vertical wall-type systems do not individually provide any support. Thus, dirt must be filled in behind them to support the newly installed paving stones. A deficiency of such systems is that when the paving stones are compacted, the backfilling operation must already have been performed. This can add time to the installation process.
Further, often landscaping is to be performed once the paving stones are in place. Thus, sod may be installed right up against the vertical wall edging. As backfilling is required for compaction, the landscaper may be forced to dig out soil to make room for sod after the paving stone installation is complete.
Not only does this add time to the job, but it presents the possibility of the landscaper accidentally ruining the integrity of the newly installed paving stone system. It would be desirable to avoid these problems by providing edging which does not require backfill to fully support the installed paving stones during compaction and/or upon completion of the installation.
Another problem associated with the preformed concrete, steel or aluminum edge restraints is that they do not provide flexibility to absorb forces and allow the material to flex back into shape after large forces such as vehicles run over a portion extending above the ground level. Therefore, in the case of aluminum edge restraints, significant deformation could occur if a heavy load is placed thereon. Once the deformation is formed, the portion of the deformed edge restraint extending could only be bent back to the proper shape with great effort.
Further, although the edge restraint patents discussed thus far serve as curbs and therefore are intended to extend above the ground, it is often desirable to provide edge restraints which do not extend above the ground level, for example, for the lining of driveways and sidewalks having an earth boundary on the outside of the edge restraint.
U.S. Pat. Nos. 1,349,340 and 1,894,395 show forms used in the pouring of concrete to hold the concrete in form while hardening. U.S. Pat. No. 1,894,395 is actually included in a poured structure as concrete is poured on either side of the center portion 3. Both of these patents are used in the different environment of concrete pouring.
As discussed above, it would be desirable to provide a lightweight edge material which uses the ground around it to provide increased strength for preventing horizontal shifting of paving stones.
Thus, an object of the invention is to provide an edge restraint to restrain paving stones in a predetermined boundary. Another object is to achieve increased restraint by utilizing the earth surrounding the edge restraint to provide support. A further object of the invention is to convert horizontal forces from paving stones into vertical forces down into the ground to provide added support for the edge restraint. Another object is to provide an edge restraint system that does not require backfilling during compaction or after installation is complete.
Other objects of the invention include providing an edge restraint with increased flexibility to facilitate maintaining irregular boundary areas and to protect the restraint from permanent damage due to unwanted permanent deformation.
Another object is to provide lightweight edge restraint which can be formed in continuous strips not requiring preformed curved sections. Another object of the invention is to provide an edge restraint which can be cut easily with a device such as a knife or with simple sawing to desired lengths and fashioned to desired curves.
Another object of the invention is to provide an edge restraint which provides increased support by converting horizontal forces into vertical forces into the ground along most of its length and not only at various points.
These objects are achieved by providing a landscaping support apparatus for edging and restraining hard surface elements in a given position on ground soil. The landscaping support apparatus includes substantially upright strip restraining elements which define a boundary around the hard surface elements. An inner surface of the upright elements faces toward the hard surface elements for receiving substantially horizontal forces from the hard surface elements. Extension elements are also provided which extend out from a surface opposite the inner surface of the upright elements. The extension elements are used for receiving vertical forces relative to the ground surface. Also provided are force converting elements for converting the horizontal forces received by the upright elements into vertical forces against the extension elements, thereby restraining the hard surface elements in the boundary.
According to advantageous features of certain preferred embodiments of the invention, the extension elements have a total length extending from the upright strip restraining elements longer than a length of the upright strip restraining elements extending from the extension elements to an upper end of the upright strip restraining elements.
According to other advantageous features of certain preferred embodiments of the invention, the force converting elements include a connecting strip extending between the extension elements and the upright strip restraining elements. In certain preferred embodiments, the upright strip restraining elements and the extension elements each include continuous strips which lie in perpendicular planes to one another. In certain preferred embodiments, the connecting elements include a connecting strip extending from the upper region of the upright strip to an outer end of the base strip, and also includes a cross strip extending from the juncture of the upright strip and the base strip to the connecting strip.
According to other advantageous features of the certain embodiments of the invention, the continuous base strip, connecting strip and cross strip include cut out portions at given intervals to provide increased flexibility to the entire landscaping support apparatus. In certain preferred embodiments holes are provided through the base strip, connecting strip and cross strip which receive stakes driven into the earth. Depending on the types of materials used for the hard surface elements such as bricks or paving stones, the intended magnitude of forces applied thereto, and the shape of the border desired, these cut out portions and stake holes are spaced predetermined distances along the landscaping support apparatus.
According to other advantageous features of certain preferred embodiments of the invention, attaching elements are included which provide a detachable mounting of at least one of the horizontal extension elements and the force converting elements to the vertical strip restraining elements. This system provides a variety of different applications of the system. In certain preferred embodiments, at least one of the horizontal extension elements and the force converting elements are included in a plurality of sections detachably disposed in spaced intervals on the vertical strip restraining elements. By spacing the detachable elements in intervals, the flexibility of the vertical strip restraining elements is increased. Thus, the system can be curved to accommodate irregular shaped paving stone boundaries.
According to other advantageous features of certain preferred embodiments of the invention, the horizontal extension elements and the force converting elements comprise separate attachment sections which are removably attached to the vertical strip restraining elements. In certain preferred embodiments, the vertical strip restraining elements are a continuous strip and the attachment sections are removably disposed in spaced intervals on the vertical strip. These preferred embodiments provide excellent flexibility for use in curved borders as well as simplicity of use.
According to other advantageous features of certain preferred embodiments of the invention, the landscaping support apparatus is a polyvinyl chloride (PVC) extrusion.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.